LWRC ICDIU3B16 ICDI Direct Impingement .300 Blackout 16.1" 1:7" 5/8x24 Bbl Black Complete Upper ReceiverThe LWRC ICDI Direct Impingement .300 Blackout Upper Receiver is a complete upper assembly designed for AR-15 rifles. It features a 16.1-inch barrel with a 1:7 twist rate and a 5/8x24 muzzle thread, which allows for various muzzle devices. The LWRC ICDIU3B16 direct impingement system is known for its simplicity and reliability. The upper receiver is finished in black and is identified by the model ICDIU3B16. It is engineered for performance and durability in the .300 Blackout caliber. LWRC ICDI Direct Impingement .300 Blackout 16.1" 1:7" 5/8x24 Bbl Black Complete Upper Receiver ICDIU3B16